Gas transfer system for liquid fuels

ABSTRACT

Liquid fuels are transferred from a fuel tank by the pressure of a liquified cyrogenic gas vaporized by heat exchange with the liquid fuel.

United States Patent [19 1 i Simon Apr. 16, 1974 GAS TRANSFER SYSTEM FOR LIQUID 62/51, /3948 FUELS Inventor: Michael Simon, [56] References cued Hamburg-0thmarschen, Germany UNITED STATES PATENTS 3,427,806 2/1969 Truax et al. 60/39.48 [73] Asslgnee- Masch'nenfabf'k Augsburg 3,440.829 4/1969 Davies-White .r 62/53 x Numbel'g Akllengesellschaft, 3,473,343 10/1969 Chamberlain v 62/45 Mun h n, r y 3,|s9,o7s 6/l965 Davidson r 62/51 x Filed Mar 7 1972 3,431,743 3/1969 Green 62/52 [21] Appl. No.2 232,548 Primary Examiner-Meyer Perlin Assistant Examiner-Ronald C. Capossela Related US. Application Data Art ,A 1, F --F. W. Tu b ll [63] Continuation-impart bf Ser. No. 79,288, Oct. 8, omeey or m a 1970, abandoned. s [52] CL 6252 60/39 48 3222/4 Liquid fuels are transferred from a fuel tank by the Y 222/394 pressure of a liquified cyrogenic gas vaporized by heat 511 Int. Cl. F17 7/02 exchange with the liquid fuel- 2 Claims, 4 Drawing Figures Field of Search 222/3, 4, 394; 62/7, 50,

invention; and

GAS TRANSFER SYSTEM FOR LIQUID FUELS This is a continuation-impart of application Ser. No.

79,288 filed Oct. 8, 1970 now abandoned; This invention relates to a supply system for compressed gas used for forcingliquid fuels from fuel tanks and .especially usedfor the, mechanism of propelling rockets by means of-cryogenic gaseswhich are liquid when cold. J h i v Supplying liquid from fuel storage tanks is accomplished either with adequate and expensive pump systems or by means of a more simple compressed gas supply system which, however, has an unfavorable supply capacity. I r

The conventional pressure gas supply systems for the most part use highly heated gasin a separate high pressure tank so that the gases come in contact with the liquid being transferred within the tank by means of the required pressure and a pressure reducing valve.

In practice such as in rocket drives a distinct -disad vantage is in that the separate pressure gas tank has an excessively great weight-which can amount to as much as the weight of the liquid storage tank when empty and given the same method of manufacture and a constant pressure in the tank.

The object of this invention is to produce a more'simple method in which the liquid fuelsand/or the liquid of the pressuregases are stored as. well as transferred without the aforementioned disadvantages.

Other and further objects and advantages of the present inventionwillappear'from the following specification taken withthe accompanying drawings in which like characters of reference refer to similar parts in the several figuresand in which:

FIG. 1 is a diagramatic showing of one form of the invention; a I

FIG. 2 is a diagramatic showing of a second form of the invention;

FIG. 3 is a diagramatic showing of a third form of the FIG. 4 -is a diagramatic showing of a fourth form of the invention. In general, the objects of this invention are obtained with a special regard to the driving system for rockets in which a liquified cryogenic gas which has a small volume and at a low pressure is used as the transfermedium for the liquid fuel propellant;

A further feature of this invention is that the heat stored in the liquid fuel to be transferred is used for heating the liquified cryogenic gas which is transformed into a gaseous state when it has passed its saturation temperature range and is then used as the pressure gas. The heating of the liquified cryogenic gas can be accomplished indifferent ways when, on one hand the liquid being transferred gives off the amount of heat necessary for the vaporization of the cryogenic gas indirectly by means of a heat exchanger as seen in FIG. 1 through which both components are passing (without being intermingled). v In FIG. 1 the liquid fuel tank discharges fuel 11 through a pipe 12 controlled by a valve 13 under the influence of gas pressure in space 14 above the liquid fuel. This gas pressure is provided from a tank 10a containing liquid cryogenic gas 15. This tank 10a may be suitably insulated so that the pressure over the gas 15 will not become excessive.

Cryogenic gas in liquid form passes through pipe 16 to a heat exchanger 17 where it is vaporized by heat 2 I from the liquid fuel 11 as it flows toward valve 13. The vapor or gas from the liquified cryogenic gas 15 is lead by pipe 18 to the top of tank 10 to enter the space 14.

"The flow of this gas may be controlled by a valve 19 in pipe 18.

The second example of the invention", as seen in FIG.

2, introduces the liquified cryogenic gas as a liquid directly into the liquid fuel being transferred, which liqion of pressure gas.

This is seen in FIG. 2, where tank 20 contains the liquid fuel 11. A tank 10a, as in FIG. 1, contains the liquified cryogenic gas 15 which is lead by pipe 16 into the tank '20 where it is introduced as a liquid by a distributer 21 into fuel 11. When the cryogenic liquid 15 comes into contact with the liquid fuel 11 it vaporizes and bubbles up into the space 14 above the fuel 11, to push the fuel down through discharge pipe 12 controlled by valvel3 as in FIG. 1. A valve 22 may be used to control the flow of the liquified cryogenic gas to tank 20.

It is noted that the temperature of the liquid being transferred drops in both FIGS. 1 and 2 by the corresponding amount of heat whichwould have had to be used for the purpose of vaporizing and heating the pressure gas to the temperature of the liquid being transferred. In. the case of the indirect heat transfer by means'of a heat exchanger in FIG. 1, there remains a certain differential amount of temperature because of the heat losses in the heat exchanger wall.

When the liquid being transferred is in itself composed of a cryogenic gas with a temperature comparable to that of the. pressure gas liquid, then the possibility for a direct and/or indirect heat exchange to the pressure gas from the liquid fuel becomes questionable. Accordingly, in FIG. 3 this invention provides the liquified pressure gas mixed with the liquid being transferred and is permitted to vaporize from the liquid surface of the mixture according to the drop in pressure in the tank when the vapor pressure above the mixed liquid drops. In this case the system is suitable only for a passively falling pressure in the tank.

This is seen in FIG. 3, where a mixture of liquid to be transferred and liquid cryogenic gas 23 is placed in tank 24. It is seen then that as the liquid to be transferred is withdrawn from the bottom of tank 24 through pipe 12 and valve 13; the pressure above the liquid level in tank 24 will drop, whereupon the liquified cryogenie gas mixed with the liquid to be transferred will vaporize to return the pressure in space 14, above the liquid, to the vapor pressure of the cryogenic gas.

A combination of the above systems provides for the conditions when the liquid being transferred as well as the pressure gas are both liquified gasses. Here it is necessary that the pressure gas is at a low temperature in order to state be able to obtain a state below the saturation temperature.

In FIG. 4, tank 10 similar to tank 10 in FIG. 1, contains liquid to be transferred 11 having a space 14 above it. A tank 10a of liquified inert cryogenic gas 15 is provided, but, instead of providing the liquid from tank the vapor developed above liquid 15 in tank 10a is lead, by a pipe 25 controlled by a valve 26, to the top of tank 10 into the space 14.

The liquid to be delivered (in cryogenic condition) may be oxygen, in the case of a rocket, or methane, CH in the case of a rocket, but also in general. The pressure gas may be liquid helium.

Having now described the means by which the objects of this invention are obtained,

I claim:

1. An apparatus for transferring liquid fuel from a tank having a discharge outlet by means of a liquified cryogenic gas comprising; providing a storage receptacle containing liquid cryogenic gas at low pressure and volume, providing an indirect heat exchanger in thetion of the liquified cryogenic gas. 

1. An apparatus for transferring liquid fuel from a tank having a discharGe outlet by means of a liquified cryogenic gas comprising; providing a storage receptacle containing liquid cryogenic gas at low pressure and volume, providing an indirect heat exchanger in the discharge outlet of said tank, providing a connection from said storage receptacle to said indirect heat exchanger so that liquid cryogenic gas will be vaporized by the heat from fuel flowing in said discharge outlet, and a connection from said indirect heat exchanger to said tank above the fuel in said tank whereby the vapor pressure of said cryogenic gas will aid in transfer of said fuel from said tank.
 2. The apparatus of claim 1, in which the pressure over the liquid fuel in the tank is preselected by selection of the liquified cryogenic gas. 